The invention relates in general to tube-launched projectiles and in particular to obturators for such projectiles.
Obturators are used on tube-launched projectiles to create a gas seal. The propellant gas behind the obturator propels the projectile out of the launching tube. Some projectiles and their obturators are designed to be launched from rifled tubes while other projectiles and their obturators are designed to be launched from smooth bore tubes. In some cases, projectiles launched from rifled tubes must have minimal or no spin. In these cases, a slip obturator is necessary. Slip obturators decouple the rifling effects of a rifled launch tube from the projectile. Slip obturators enable fin-stabilized munitions to be launched from rifled barrels with a minimum of barrel-induced spin or from smooth barrels with no barrel-induced spin.
The testing of a projectile may include launching the projectile from a tube. The propellant gas pressure in the tube may be very high. Gas pressures can be as high as 125% of the permissible maximum operating pressure for the projectile, for example, as high as 75,000 psi for artillery. Specially designed cannon and breech combinations are used to conduct high pressure testing of projectiles. The obturator used on a projectile during high pressure testing or other high pressure use must provide a high pressure gas seal. If the launch tube is equipped with a muzzle brake, it is preferable that the obturator remains intact and on the projectile through the muzzle brake and after muzzle exit as the projectile clears the weapon, or else the discarded obturator or parts of it may damage or destroy the muzzle brake and/or other equipment and personnel.
Examples of obturators are disclosed in U.S. Pat. No. 3,760,736 issued on Sep. 25, 1973; U.S. Pat. No. 6,085,660 issued on Jul. 11, 2000; U.S. Pat. No. 4,109,582 issued on Aug. 29, 1978; U.S. Pat. No. 4,242,961 issued on Jan. 6, 1981; and U.S. Pat. No. 5,164,540 issued on Nov. 17, 1992.
A need exists for obturators for projectiles subject to very high pressures, and for high pressure obturators that remain intact and on the projectile after muzzle exit.